Partitioning mycorrhizal influence on water relations of Phaseolus vulgaris into soil and plant components

Abstract

There is growing appreciation of arbuscular mycorrhizal effects on soil properties and their potential consequences on plant behavior. We examined the possibility that mycorrhizal soil may directly influence plant water relations. Using wild-type and noncolonizing bean mutants planted into soils previously produced using mycorrhizal or nonmycorrhizal sorghum plants, we partitioned mycorrhizal influence on stomatal conductance and drought resistance into soil and root components, testing whether effects of mycorrhizal fungi occurred mostly via mycorrhization of roots, mycorrhization of soil, or both. The mutation itself had no effect on any water relations parameter. Colonization by Gigaspora margarita Gerdemann & Trappe and Glomus intraradices Schenck & Smith had appreciable effects on leaf water potential at the lethal point and on osmotic adjustment, relative to nonmycorrhizal plants of comparable size. Mycorrhizal effects on drought resistance were attributable to an effect on the plant itself rather than to an effect of mycorrhizal soil. Mycorrhizal effects on stomatal conductance were attributable to mycorrhization of both roots and soil, as well as to mycorrhization of roots alone. Surprisingly, merely growing in a mycorrhizal soil resulted in promotion of stomatal conductance of nonmycorrhizal plants in both amply watered and droughted plants. Mycorrhizal effects on droughted plants did not appear to be related to altered soil water retention properties, as Gigaspora margarita and Glomus intraradices altered the soil's moisture characteristic curve only slightly.Résumé : On reconnaît de plus en plus les effets des mycorhizes arbusculaires sur les propriétés du sol et leurs consé-quences potentielles sur le comportement de la plante. Les auteurs ont examiné la possibilité que le sol mycorhizé puisse influencer directement les relations hydriques de la plante. À cette fin, ils ont utilisé une race sauvage de haricot ainsi qu'un mutant non colonisant, plantés dans des sols préalablement produits avec des plants de sorgho mycorhizés ou non mycorhizés. Ils ont ensuite réparti l'influence des mycorhizes sur la conductance stomatale et la résistance à la sécheresse entre les composantes sol et racines, la mycorhization du sol, ou les deux. La mutation elle-même est sans effet sur l'ensemble des paramètres hydriques. La colonisation par le Gigaspora margarita Gerdemann & Trappe et le Glomus intraradices Schenck & Smith a des effets manifestes sur le potentiel hydrique foliaire au point létal, et sur l'ajustement osmotique, par rapport à des plants non mycorhizés de grosseur comparable. On attribue les effets de la mycorhization sur la résistance à la sécheresse à une action sur la plante elle même plutôt qu'à un effet du sol mycorhizé. Dans le cas de la conductance stomatale, les effets des mycorhizes sont attribuables à la mycorhization à la fois des racines et du sol, aussi bien qu'à la mycorhization des racines prises séparément. Il est surprenant de constater que le seul fait de croître dans un sol mycorhizé a...

Arbuscular mycorrhizae and soil/plant water relations

“…Colonization by Gi. margarita and G. intraradices had appreciable effects on lethal leaf Ψ and osmotic adjustment, relative to nonAM plants of comparable size (Augé et al 2004b). Mycorrhizal effects on drought resistance were attributable to an effect on the plant itself rather than to an effect on soil colonization.…”

“…Their importance lies in the fact that a small but significant mycorrhizal effect on water retention properties was evident after only 7 mo of mycorrhizal colonization of soil and with similar root densities as nonAM soils. We postulated that mycorrhizal influences are apt to become more substantial over longer time periods and repeated the experiment, developing mycorrhizal soils for 12 mo (Augé et al 2004b). As mycorrhizal fungal species can differ in their production of glomalin and extraradical hyphae, we added a second AM treatment, colonizing soil with Gigaspora margarita Gerdemann & Trappe as well as with G. intraradices.…”

“…Using wild type plants (myc+) and non-colonizing mutants (myc-) of Phaseolus vulgaris L. planted into previously produced mycorrhizal and nonmycorrhizal soils, we partitioned mycorrhizal influence on g s and drought resistance into soil and root components, testing whether effects of mycorrhizal fungi occurred mostly via plant colonization, soil colonization, or both (Augé et al 2004b). Using myc-mutants allowed the influence of mycorrhizal colonization of roots to be uncoupled from mycorrhizal colonization of the soil in which plant roots were growing.…”

Arbuscular Mycorrhizal Fertilization Of Corn (Zea mays L.) Cultivated on Ferrous Soil in Southern Benin

“…In station, the seedlings of fonio (Digitaria exilis Stapf) inoculated with arbuscular mycorrhizal fungi (G. manihotis) had an increase (+ 28.5%) compared to the seedlings controls (Ndoye et al, 2016). Augé et al (2004) explained the growth improvement by a better water absorption, while Yamawaki et al (2013) and Sharma et al (2016) explain it by a better absorption of mineral manures.…”

“…AMFs play an important part in plant phosphorus absorption, mainly in tropical areas where the soil content of available phosphorus is very weak (Matos et al, 1999). Also, the AMF facilitate the phosphorus mobilization through the "hyphae" system (Ndoye et al, 2016) and a better water absorption (Augé et al, 2004) and in biogenic salts (Sharma et al, 2016). Moreover, they contribute to the restoration of damaged grounds (Zhang et al, 2016).…”